I noticed yesterday that my carriage gibs were starting to get loose after all the use and break in, so this afternoon I decided to pull that all apart and give it a good cleaning and inspection. It had bothered me that there were certain parts I hadn't been able to clean without disassembling it, so no time like the present. Turns out there was a lot more black, gritty mill scale under the carriage than I had suspected, so it was a good thing. The gibs that ride under the bed need to be level and tensioned with a series of screws and set screws, and one of the set screws doesn't have a lock nut due to being located directly above the handwheel gear, so it got a little bit of threadlocker when I put it back. All the screws and threaded holes need a good cleaning and blow-dry with compressed air. I pulled the back shield off and the apron off the carriage in order to access the gib screws, then after cleaning and oiling everything put it back together, being careful to keep the gibs nice and level with the bed ways via the set screws when snugging everything down. After getting all that done I discovered the leadscrew didn't perfectly align with the half nuts, even after adjusting the apron position repeatedly. The leadscrew actually wasn't parallel to the bedways on either axis, so more teardown required and I had to slot the screw holes on both leadscrew bearing blocks to finally get it in the correct position to not flex or bind when the half-nuts were engaged. A .005" shim behind the tailstock end bearing block brought the leadscrew out to parallel that way, and after removing the control panel housing and leadscrew block on the headstock end for hole enlargement, I finally got the leadscrew moved up enough to run perfectly centered in the half nuts and not bind no matter where the carriage is located.
A note on the leadscrew blocks. The one on the headstock end isn't accessible without removing the control panel, and there is nothing in the instructions about oiling it. I had wondered about that since there is a ball oiler on the other one. Well, there's an oil HOLE, but no oiler on the left one. You will want to remover the switch panel, leadscrew end gear, banjo, and block and clean all the nasty gunk out of it all (including the bearing block mounting holes) and make sure the oil hole in the block is clear and clean. Oil the leadscrew bearing surface and inside of the block, then fill the oil hole up before putting it back together. I thought about greasing it since it's not easily accessible, and that may be what was intended, but everything else on the machine takes oil so I stuck with that.
This is all a royal pain and takes a lot of patience and thought, but if you go through it sooner than later (and disassemble, clean, and adjust all the other gibs and leadscrews while you're at it) I think the machines will last a lot longer.
